System for fluid decontamination

ABSTRACT

A system for removing contaminants such as dissolved and entrained gas, water and solids from fluids. Contaminated fluid is atomized and filmed in a very low pressure vacuum to remove gas and water. Filters are provided for removal of solids. Decontaminated fluid may be transferred within the system and withdrawn from the system without recontamination.

United States Patent 1 Magorien et al.

[54] SYSTEM FOR FLUID DECONTAMINATION [75] 1nventors:Vincent G.Magorien, Granada Hills; John A. Huffman, North'- ridge, both of Calif.

Assignee: Seaton-Wilson Incorporated, Burbank, Calif.

Filed: Jan. 28, 1971 Appl. No.: 110,477

US. Cl ..55/194, 208/186 Int. Cl. Field of Search ..55/41, 43, 189, 190,

[56] References Cited UNITED STATES PATENTS 3,357,161 12/1967 Starr etaI ..55/189 1 Apr. 10, 1973 3,538,682 11/1970 Chattin et ..55/189 X2,797,767 7/1957 2,990,030 6/1961 1,836,338 12/1931 Rodman et al...55/194 X Primary ExaminerSamih N. Zaharna Assistant Examiner-R. W.Burks Attorney-Fulwider, Patton, Rieber, Lee & Utecht [5 7] ABSTRACT Asystem for removing contaminants such as dissolved and entrained gas,water and solids from fluids. Contaminated fluid is atomized and filmedin a very low pressure vacuum to remove gas and water. Filters areprovided for removal of solids. Decontaminated fluid may be transferredwithin the system and withdrawn from the system without recontamination.

12 Claims, 1 Drawing Figure SYSTEM FOR FLUID DECONTAMINATION BACKGROUNDOF THE INVENTION 1. Field of the Invention This invention relates todevices for separating gases from liquids and, more particularly, to avacuum system in which the contaminated liquid is atomized and filmedfor decontamination. Further, the invention includes a new and improvedapparatus for transferring the liquid, both before and after treatment,to insure that the treated liquid is not recontaminated by exposure togases and air.

2. State of the Prior Art In many types of systems, fluids are used insuch a way that it is of the utmost importance to keep them free fromcontaminants of all kinds. Three types of contaminants, gas, water andsolids, may act to so change the important properties of liquids as torender them unsuitable for their intended use.

For example, fluids are used as the power transmitting means inhydraulic systems. For such a system to work as intended, the fluid mustbe free of all contaminants. It may be readily appreciated that solidparticles in a hydraulic system would erode parts, cause binding ofmoving parts, and so forth. Also well understood is the undesirableeffects of pockets of free gas, such as air, within a hydraulic system.However, less well understood are the effects of dissolved gas inhydraulic fluids.

Gas can become dissolved in fluids such as the various petroleumderivatives utilized in hydraulic systems. Molecules of gas, indissolving, become distributed throughout the fluid, interspersed amongthe much larger liquid molecules. When dissolved, the gas does notbehave according to Boyles law. It does not affect the bulk modulus ofthe solvent fluid. Accordingly, if the air were to remain dissolved, noproblems would be created within a hydraulic system.

Dissolved gas, however, does obey Henrys law: the quantity of gasdissolved in a liquid is directly proportional to the partial pressureof the ga s. Therefore, as the pressures within the hydraulic systemchange, the gas may go out of solution and become entrained. Thereafter,the gas acts as in any hydraulic system containing free gas: hydraulicfluid is caused to foam, power is lost, control is spongy, the bulkmodulus of the fluid is lowered, and so forth. Because the gas is heldin solution, however, the usual practice of bleeding the contaminatedhydraulic system does not work. Also,

bleeding may not even remove entrained gas where the gas is contained insmall bubbles distributed throughout the fluid.

Similar problems are encountered when fluids are used as dielectrics invarious electrical components. In-

dustrial power transformers, for example, utilize fluids as both adielectric and a cooling medium. Very small amounts of solids and waterwithin a dielectric fluid can easily halve its breakdown voltage.Similarly, experimental data indicates that dissolved or entrained gasmay reduce the breakdown voltage of a dielectric fluid as much as 40percent. It is, therefore, of the utmost importance to remove water anddissolved gases from dielectric fluids.

Various types of devices have been utilized in the prior art to removecontaminants from fluids; Filters,

for example, can readily remove solids. It is also known to removedissolved and entrained gas by subjecting the contaminated fluid to avacuum. As predicted by Henrys law, a decrease of pressure above thefluid results in the dissolved gas passing from solution. Unfortunately,however, creation of a vacuum above a fluid generally results in a greatamount of foaming. Quite often, the amount of sudsing renders largeamounts of the fluid unuseable. In addition, foam will generally foulthe source of vacuum used. Finally, since gas can only be drawn offafter foam has collapsed, foaming causes a substantial increase inprocess time.

SUMMARY OF THE INVENTION In accordance with this invention, provision ismade for the decontamination of fluids. Solids are removed by the systemin appropriately placed filters. The fluid is then atomized inside acontainer in which a vacuum has been created. Dissolved gas is passedout of solution immediately when the vacuum is encountered. Atomizationserves to break the fluid into droplets of such small size that thepreviously dissolved gas escapes from the fluid without the creation offoam and suds. Additionally, the atomized fluid collects and films onsurfaces where it is further degassed.

Provision is also made for transfer of the fluid into and out of thedecontamination system without the use of means which would serve torecontaminate or further contaminate the fluid. Transfer is accomplishedby creating a lower pressure in the destination container than in thesource container. In this way, contact of the fluid with contaminatinggas or air is held to a minimum.

Further, for those instances where fluid will be retained in the systemfor a long period of time, the invention provides for recirculation ofthe purified fluid through the decontamination stages to remove any airthat may have passed into solution during the storage time.

DESCRIPTION OF THE DRAWINGS The FIGURE illustrates theinterrelationships of the various components of this invention.

DETAILED DESCRIPTION OF THE INVENTION In accordance with this invention,fluid is pumped from a storage or shipping container by a vacuum lineconnected to an aspirator. The latter is a well known device in which aventuri is placed in a pumped fluid stream to create a partial vacuum.As the fluid drawn into the system by the aspirator enters the holdingtank,

va vacuum is created in the decontaminating tank by a vacuum pump.

When the vacuum reaches a predetermined value, the fluid is pumped fromthe holding tank to the decontaminating tank through an atomizer. As theatomized fluid enters the tank, dissolved gas is released from solutionand drawn off by the vacuum line. At the same time, dissolved water isvaporized and drawn off since the decontaminating tank is at a pressuremuch lower than the vapor pressure of water at the system temperature.

As the decontaminated fluid collects in the decontamination tank, itslevel rises. When a maximum level is reached, the fluid input is turnedoff and the decontaminated fluid drawn to a storage reservoir where itis held until needed. No fluid pump is used in the transfer forconsiderations of simplicity and reliability.

Decontaminated fluid may be drawn from the reservoir for use orrecirculated to the decontamination tank. The latter procedure isutilized when the fluid has been stored for an extended length of timeor if additional decontamination is desired. 1f drawn for use, the fluidis again transferred by vacuum levels so that contact with air isminimized.

This invention removes contaminants to an amount heretofore not reachedin the art. For example, this invention has been used to removedissolved air from saturated Coolanol silicate ester dielectric fluid.Prior to decontamination, the fluid contained about 170 parts permillion by weight of air. After decontamination by the apparatus of thisinvention, the dissolved air content was measured at 4 parts per millionby weight. Measurements in each case were taken by the apparatus ofU.S.Pat. No. 3,521,478.

Referring to the FIGURE, the decontamination system is illustratedconnected to a shipping or storage container 10. The various fluid, ventand vacuum lines are shown controlled by solenoid valves, such as 11, 12and 13, and manual valves, such as 14. All such valves, which may, ofcourse, take different forms, are initially closed.

Before the system is turned on, it is necessary that a small amount offluid be introduced into holding tank 16. This fluid is pumped throughaspirator 17 in a closed loop to create the vacuum necessary to drawfluid from container 10.

When the system is turned on, vacuum pump 18, hydraulic pump 19 andvalves 11, 20 are turned on. The residue of fluid is pumped from holdingtank 16 via line 21 and aspirator 17 and returned via line 22. Theless-than-atmospheric pressure induced in line 24 by the aspiratorimmediately begins to draw fluid from container through filter 25. Inthe preferred embodiment,f1lter 25 is a depth-type filter.

As fluid is withdrawn from container 10, gas is drawn into the containerthrough desiccant connector 28. The purpose of the desiccant connector,of course, is to ensure that no water vapor enters container 10 to bedissolved in the fluid.

Holding tank 16 is connected to the atmosphere via vent lines 30, 31 andfilter 32. As it is being filled by fluid drawn from container 10,vacuum pump 18 is creating a vacuum within decontamination tank 34.

Pump 18 is connected to decontamination tank 34 by vacuum lines 35, 36and cold trap 37. The trap is a standard device in high vacuum systemsused to protect pump 18 from vapors in any of the vacuum lines. Liquidnitrogen is placed in the trap to condense any such vapor drawn in fromany of the various lines.

When the vacuum in decontamination tank 34 reaches a low level, about500 microns of mercury in the preferred embodiment, as measured by gauge34, valve 40 is opened. Some of the fluid from pump 19 is then connectedto atomizer 41 via line 42.

Atomizer 41 is a most important element of this invention. It is used toreduce the fluid to droplets of sufficiently small size so that thedissolved and entrained gas is drawn off via vacuum line 35 without theformation of foam or suds. It is believed by the inventors that maximumdroplet sizes of approximately 0.010 inch in diameter are necessary forfoaming not to take place. At any rate, it has been found thatsatisfactory decontamination occurs without foaming with about p.s.i.g.,as measured by gauge 45, pressure in line 42 and an equilibrium pressureof about 700 microns of mercury in decontamination tank 34. Atomizer 41,in the preferred embodiment, is a Type 1/4 M6 Brass nozzle, manufacturedby Spraying Systems Co., Bellwood, Illinois.

As the decontaminated fluid collects within decontamination tank 34,float 43 rises on column 44. The main purpose of float 43 is to protectthe upper surface of the collected fluid from contamination during thetransfer cycle as air is introduced for transfer. Accordingly, the floatis sized as closely as possible to the inside diameter of thedecontamination tank. In addition, the sloping upper surface of thefloat, along with the interior walls of the tank, serve to film thecollecting fluid. This removes any dissolved or entrained gas which mayremain after atomization. Further, the lower surface of the float isshaped like an inverted cove so that no contaminants will be trappedbeneath the float.

The flow rates, in the preferred embodiment, are adjusted so thatslightly more fluid is drawn in from container 10 than is pumped todecontamination tank 34 via line 42. Accordingly, the fluid level inholding tank 16 generally rises slowly even after valve 40 opens.

Holding tank 16 includes level tube 46 connected to the tank via lines48, 48. At the top of level tube 46 is switch 50, which operates whenthe fluid level reaches its level. Switch 49 operates when the fluidlevel falls to that point.

The sequence described above continues until the fluid level in holdingtank 16 reaches switch 50. This causes valve 11 to be turned off,stopping the withdrawal of fluid from container 10. Valve 52, whichwould be on during the recirculate mode, is turned off if the system hadbeen in that mode. The recirculate mode will be explained in detailbelow.

After valve 11 closes, fluid is pumped into decontamination tank 34until that stage fills, as detected by switch 53 in level tube 54. Valve11 will be reopened when the fluid level drops below switch 50. When thefluid level in the holding tank reaches switch 49, as would happen ifcontainer 10 becomes empty, valve 40 closes to maintain a supply offluid for pump 19 to recirculate. Without this initial amount of fluid,pump 19 would be damaged and aspirator 17 would not operate.

When decontamination tank 34 is filled, the fact is indicated by theclosure of switch 53 in level tube 54. This causes valves 40 and 20 toclose, shutting off the fluid supplied to atomizer 41 and the vacuumsource from tank 34. At the same time, valves 12 and 56 open, connectingthe vacuum source to reservoir 58 via line 59 and ventingdecontamination tank 34 to the atmosphere via line 60.

Reservoir 58 is a closed container connected to decontamination tank 34via line 61 and check valve 62. The reservoir contains a free-floatingfloat 63. As before, the purpose of float 63 is to protect the uppersurface of the decontaminated fluid from the air in the upper portion ofthe reservoir during fluid transfer. Ac-

cordingly, float 63 is made as nearly as possible the same dimension asthe inside diameter of reservoir 58.

In addition to being connected to the source of vacuum via line 59,reservoir 58 is also connected to the atmosphere via line 31 andconstriction 65. The pressure, then, in reservoir 58 is held at a rangeof values between that of the vacuum source and the atmosphere.Decontamination tank 34 is vented to the atmosphere and is, therefore,at a higher pressure than reservoir 58. Fluid is thereby drawn fromdecontamination tank 34 to reservoir 58 via line 61.

Reservoir 58 is preferably sized larger than decontamination tank 34 sothat it can receive several cycles from the decontamination tank beforefilling. When the decontamination tank empties, switch 67 reverses thecontrols of switch 53, thereby closing valve 56, opening valve andclosing valve 12. Valve 40 will be opened when the vacuum level withinmain stage 34 reaches approximately 500 microns of mercury. Thereafter,the process repeats as described above.

The sequence described continues until reservoir 58 is filled. Switch 70in level tube 71 senses that the reservoir is filled and closes valve 11and opens valve 52 placing the system in the recirculate mode. Valve 72is held on as long as fluid covers switch 98. The system now operates asdescribed above, except that the source of fluid is now reservoir 58 vialine 80 rather than container 10. This sequence continues until stoppedby a master switch. While a single cycle has been found sufficient fordecontaminating to a level suitable for nearly all applications, furthercycles will remove dissolvedgas to even lower levels. In addition, thesystem may be placed in the recirculate mode if the reservoir hasremained filled for an extended period of time.

Many different methods may be utilized to withdraw fluid from reservoir58 for use. Obviously, fluid must be withdrawn in such a fashion so asnot to be recontaminated. For example, connector 100 may be simplysealed to the device to be filled after which the device is evacuated.The pressure difference between the device and reservoir 58 may then beused to cause the decontaminated fluid to be transferred to the device.

Another method is illustrated in the FIGURE. In the filling methodindicated, only one opening to the device to be filled is available.

Via line 87, the device to be filled is evacuated by vacuum pump 18.Trickle fill line 87 is sealed to the device and fluid allowed totrickle in. This is necessary so that whatever air is left can risethrough line 87 as the fluid descends.

Trickle fill chamber 75 consists of two portions 76, 77. Generally,portions 76 and 77 are sized to contain enough fluid to completely fillthe device being filled. To fill chamber 75, valve 13 is first opened tocreate a vacuum within the chamber. Valve 14 is then opened, causingfluid to be transferred from reservoir 58 to chamber 75 via check valve81, filter 82 and line 83. This continues until the chamber is filled,as sensed by switch 84 in level tube 85. Valves 13 and 14 are thenclosed.

In those instances where the device must be filled to a predeterminedpressure, compressor 90 is switched on after the device is filled. Valve95 is adjusted to obtain the desired pressure on gauge 91. When gauge 91registers the desired pressure, valve 92 is opened allowing chamber 75to also reach the desired filling pressure. The device being filled isthen disconnected.

Compressor 90 is then turned off and the pressure in chamber reducesthrough vent valve 95. Valve 92 is then closed.

It is noted that upper portion 76 of chamber 75 is provided with a floatconstruction 97 like that in main chamber 34. Notwithstanding float 97,some contamination of the outer portions of the fluid in chamber 75takes place, especially when the chamber is connected to the higherpressure produced by compressor 90. Accordingly, it is generallyadvisable to completely purge the fluid in chamber 75 remaining aftereach filling. The purged fluid may then be recycled to remove thedissolved air.

Lower switches 97, 98 in level tubes 85, 71 may be used as safetydevices to signal the fact of the respective containers having beenemptied. Similarly, hydraulic pump 19 is provided with the usual safetyvalve 99 to protect the motor.

We claim:

1'. In a system for decontaminatin-g fluid, the combination comprising asource of contaminated fluid,

means for withdrawing fluid from said source and raising the withdrawnfluid to an elevated pressure,

closed container means, means for selectively evacuating said closedcontainer means to create a partial vacuum therein,

means connected to receive said fluid at an elevated pressure foratomizing said fluid within said closed container means, means connectedto said closed container means for storing the fluid that forms aftersaid atomization,

means for selectively adjusting; the pressure in said closed containermeans and said storing means for causing a flow of said fluid to saidstoring means, and,

first and second float means within said closed container means and saidstoring means for floating on and substantially covering the surface ofcontained fluid.

2. The fluid decontamination system of claim 1, wherein said means foratomizing is a nozzle which produces fluid droplets having a maximumdiameter of 0.01 inch.

3. In a system for decontaminating fluid, the combination comprising asource of contaminated fluid,

first closed container means,

means for transferring fluid from said source to said first closedcontainer means,

means for withdrawing fluid from said first closed container means andraising the withdrawn fluid to an elevated pressure,

second closed container means,

means for selectively evacuating said second closed container means tocreate a partial vacuum therein,

means connected to receive said fluid at an elevated pressure foratomizing said fluid and injecting the atomized fluid into said secondclosed container means,

means connected to said second closed container means for storing thefluid that forms after said atomization,

means for selectively adjusting the pressure in said second closedcontainer means and said storing means for causing a flow of said fluidto said storing means, and,

first and second float means within said second closed container meansand said storing means for floating on the surface of and substantiallycovering contained fluid.

4. The fluid decontamination system of claim 3, wherein said means foratomizing produces fluid droplets having a maximum diameter of 0.01inch.

5. In a system for decontaminating fluid, the combination comprising asource of contaminated fluid,

a first closed container means,

a second closed container means,

means for moving contaminated fluid from said source to said firstcontainer means and from said first container means to said secondcontainer means,

means connected to receive said fluid from said first container meansfor atomizing said fluid and injecting it into said second containermeans,

means for selectively evacuating said second container means to create apartial vacuum therein,

a third closed container means,

means for selectively adjusting the pressure in said second and thirdclosed container means for causing a flow of said fluid to said thirdcontainer means, and,

float means within said second and third closed container means forfloating on the surface of the contained fluid.

6. The fluid decontamination system of claim 5, wherein said means foratomizing produces fluid droplets having a maximum diameter of 0.01inch.

7. The fluid decontamination system of claim 5, further comprising afourth'closed container means, consisting of first and second chambers,

means for selectively adjusting the pressure in said third and fourthcontainer means for causing a flow of liquid from said third containermeans to said fourth container means, and,

means for connecting said second chamber to a device being filled withsaid fluid.

8. The fluid decontamination system of claim 7, further comprising meansfor selectively raising the pressure in said fourth container means.

9. In a system for decontaminating fluid, the combination comprising afirst closed container means,

means connected to receive fluid to be decontaminated for atomizing saidfluid within said first closed container means,

a second closed container means,

means for selectively adjusting the pressure between said first andsecond closed container means for causing a flow of fluid from saidfirst closed con tainer means to said second closed container means,and,

float means within said second closed container means for floating uponand substantially covering the surface of contained fluid. 10. Thesystem for decontammatmg fluid of claim 9,

further comprising second float means within said first closed containerfor floating upon and substantially covering the surface of containedfluid.

11. The system for decontaminating fluid of claim 9, further comprisingmeans for selectively evacuating said first closed container means tocreate a partial vacuum therein.

12. The system for decontaminating fluid of claim 9, further comprisingsecond float means within said first closed container for floating uponand substantially covering the surface of contained fluid, and, meansfor selectively evacuating said first closed container means to create apartial vacuum therein.

1. In a system for decontaminating fluid, the combination comprising asource of contaminated fluid, means for withdrawing fluid from saidsource and raising the withdrawn fluid to an elevated pressure, closedcontainer means, means for selectively evacuating said closed containermeans to create a partial vacuum therein, means connected to receivesaid fluid at an elevated pressure for atomizing said fluid within saidclosed container means, means connected to said closed container meansfor storing the fluid that forms after said atomization, means forselectively adjusting the pressure in said closed container means andsaid storing means for causing a flow of said fluid to said storingmeans, and, first and second float means within said closed containermeans and said storing means for floating on and substantially coveringthe surface of contained fluid.
 2. The fluid decontamination system ofclaim 1, wherein said means for atomizing is a nozzle which producesfluid droplets having a maximum diameter of 0.01 inch.
 3. In a systemfor decontaminating fluid, the combination comprising a source ofcontaminated fluid, first closed container means, means for transferringfluid from said source to said first closed container means, means forwithdrawing fluid from said first closed container means and raising thewithdrawn fluid to an elevated pressure, second closed container means,means for selectively evacuating said second closed container means tocreate a partial vacuum therein, means connected to receive said fluidat an elevated pressure for atomizing said fluid and injecting theatomized fluid into said second closed container means, means connectedto said second closed container means for storing the fluid that formsafter said atomization, means for selectively adjusting the pressure insaid second closed container means and said storing means for causing aflow of said fluid to said storing means, and, first and second floatmeans within said second closed container means and said storing meansfor floating on the surface of and substantially covering containedfluid.
 4. The fluid decontamination system of claim 3, wherein saidmeans for atomizing produces fluid droplets having a maximum diameter of0.01 inch.
 5. In a system for decontaminating fluid, the combinationcomprising a source of contaminated fluid, a first closed containermeans, a second closed container means, means for moving contaminatedfluid from said source to said first container means and from said firstcontainer means to said second container means, means connected toreceive said fluid from said first container means for atomizing saidfluid and injecting it into said second container means, means forselectively evacuating said second container means to create a partialvacuum therein, a third closed container means, means for selectivelyadjusting the pressure in said second and third closed container meansfor causing a flow of said fluid to said third container means, and,float means within said second and third closed container means forfloating on the surface of the contained fluid.
 6. The fluiddecontamination system of claim 5, wherein said means for atomizingproduces fluid droplets having a maximum diameter of 0.01 inch.
 7. Thefluid decontamination system of claim 5, further comprising a fourthclosed container means, consisting of first and second chambers, meansfor selectively adjusting the pressure in said third and fourthcontainer means for causing a flow of liquid from said third containermeans to said fourth container means, and, means for connecting saidsecond chamber to a device being filled with said fluid.
 8. The fluiddecontamination system of claim 7, further comprising means forselectively raising the pressure in said fourth container means.
 9. In asystem for decontaminating fluid, the combination comprising a firstclosed container means, means connected to receive fluid to bedecontaminated for atomizing said fluid within said first closedcontainer means, a second closed container means, means for selectivelyadjusting the pressure between said first and second closed containermeans for causing a flow of fluid from said first closed container meansto said second closed container means, and, float means within saidsecond closed container means for floating upon and substantiallycovering the surface of contained fluid.
 10. The system fordecontaminating fluid of claim 9, further comprising second float meanswithin said first closed container for floating upon and substantiallycovering the surface of contained fluid.
 11. The system fordecontaminating fluid of claim 9, further comprising means forselectively evacuating said first closed container means to create apartial vacuum therein.
 12. The system for decontaminating fluid ofclaim 9, further comprising second float means within said first closedcontainer for floating upon and substantially covering the surface ofcontained fluid, and, means for selectively evacuating said first closedcontainer means to create a partial vacuum therein.